Electrical indicator for free piston units



0d' 1.8, 1949 A. KALrrlNsKY 2,485,154

ELECTRICAL INDICATOR FOR FREE PISTON UNITS www@ DCL 18, 1949 A. KALlTlNsKY Y 2,485,154

ELECTRICAL INDICATOR FOR FREE PISTON UNITS Filed Jan. so, 1945 l s sheets-sheet 2 QQ* coro d mN o@ aoeol S N g 9 u.

INVENTOR 0MM Mm Oct. 18, 1949. A. KALITINSKY- ELECTRICAL INDICATOR FOR FREE PISTON UNITS Filed Jan. so, 1945 3 Sheets-Sheet 5 FIG.3.

INVENTOR mam Mm Patented Oct. 18, 1949 mc'rmclu. mmcs'ron Fon FREE I ms'ron Um'rs Andrew Kalitinsky, Eaxieviile, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation oi Delaware Application January so, 1945, serial No. 575,336

l This invention relates to an electrical stroke indicator for free-piston units. y

The copending Kalitinsky application, Serial No. 550,883. now Patent No. 2,420,483 dated May 13, 1947, describes a stroke indicator which produces changes in the fluid pressure in a circuit proportional to the changes in the actual end position of the piston stroke. The changes in pressure vare used t adjust certain control devices for the unit such as a compression vcontrol for the air spring, a fuel timing'control, a control for the eifective volume ofthe compressor cylinder or other controls. A feature of this invention is an electrical device by which to indicate changes in the length or position of the piston stroke.

Another feature is a stroke indicator for producing changes in an electrical circuit proportional to changes in the actual end position of the piston stroke.

A feature of the invention is a device by which to indicate electrically the actual end position of the piston strokes with respect to the extreme end position of the stroke. Another feature is the continuous electrical indication by changes in an electrical circuit of the changes in the actual end position of the piston strokes, such that y these changes may be used in adjusting certain control devices for the unit. A feature of the invention is the electrical control of an actuating device in response to changes in the end position of the piston strokes by which to control a variable operating condition of the unit.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

Fig. 1 is a sectional view through the unit.

Fig. 2 is a sectional view of the restraining lint:- age and the master control.

Fig. 3 is a diagram of an electrical circuit including the control.

The unit shown includes an engine cylinder I8 having reciprocating pistons I2 and I4 to which compressor pistons I6 and I8 in cylinders 28 and 22 are integrally connected. Sleeves 24 and 26.

attached to the compressor piston complete the reciprocating piston assemblies. These sleeves in combination with stationary pistons 28 and 88 form air spring cylinders.

The piston assemblies are moved apart by the burning of fuel injected into engine cylinder I8 through one or more nozzles 32. Airv compressed in the air spring cylinders on the power stroke returns the piston assemblies. The assemblies are always maintained at equal distancesv from l0 Claims. (Cl. 230-56) the center of the engine cylinder by a linkage which may include racks 84 and 86, Fig. 2, ex tending from the piston assemblies and meshing with a pinion 38 on a vshaft 48.

Intake manifold 42 which extends around the compressor and engine cylinders conducts air to intake valves 44 in the heads of the compressor cylinders through which air alternately enters opposite endsof the compressor cylinders. The

compressed air leaves the cylinders through discharge valves 46 also at opposite ends of the compressor cylinders and passes into a central scavenge chamber 48 and end chambers 68 and 52. These chambers may be connected by a scavenge manifold, not shown.

Compressed gas from the scavenge chambers enters engine ports 54 and 56 which are uncovered by pistons I2 and I4 at the end of the power stroke, thereby permitting air to be blown through the engine cylinder. Gas in the engine cylinder is discharged through exhaust ports 58 into exhaust manifold 88.

The positions of the pistons at the outer ends of the piston strokes are indicated by a master control 62 actuated by a.' cam 64 on the shaft 48.

Since the pinion 38 on this shaft is oscillated directly from the pistons, movement of cam 84 is proportional to the piston stroke.

The stroke indicator includes a follower 66 carrying a roller 88 engaging with cam 64.` The follower 66 engages and moves a rod 18 adjacent the outer end of the reciprocatlon of the follower. The rod 18 has an integral plunger 12 in a chamber 14 in a casing 16. A spring 18 holds the roller 68 against the cam. A spring 88 moves the rod 18 toward the follower, its rate of move ment being limited by the plunger which acts as a dashpot and allows the rod to move only a short distance between successive strokes of follower Rod 'i8 carries an induction coil 82 movable in relation to a fixed coil 84 which may have an open iron core 85 and be shielded by a cover 86.

As shown in Fig. 3 the coil 84 is in series with Aother coils 88 and 88 in a circuit 82 which in- 85 includes the coil 88 and resistances |82.

Assuming for the moment that the contacts I I2 and ||4 which engage the resistances |00 and |82 are ilxed, and considering instantaneous voltages, a change in the normal position of coil 82 with respect to the surrounding coil 84 will cause an unbalance in circuits |08 and H0, thereby energizing a coil H6, the ends ot which are connected to contacts ||2 and I4. It will be understood that the circuits |08 and ||0 are in balance when the actual end of the stroke of the piston assemblies is normal, and a change in the actual end position of the stroke will unbalance the circuits.

Adjacent to coil ||6 is a coil ||8 in series in a circuit |20 with the grids |22 and |24 of a vacuum tube |28. A central tap in coil ||8 is connected to the cathode |28 of the vacuum tube, and this cathode is also connected to one lead of a coil |30 located in fixed relation to coil 90.

The two plates |3| and |32 of the vacuum tube are connected in series with coils |34 and |86, respectively, and the interconnected ends of these coils are connected to the other lead of coil |30. The coils |34 and |38 are in a position to move a switch bar |38 which controls the direction of rotation of a reversible motor |40 in a circuit |42 which includes contacts |44 and |48 engageable selectively by bar |38.

In operation, when the circuits |08 and I|0 are in balance, there is no electrical energy in circuit` |20. If the circuits |08 and ||0 become unbalanced, by a change in the end position of the piston stroke, coil I8 is energized, thereby inducing a flow of electrical energy in coil ||8 to activate the grids |22 and |24. If the electrical impulses in the circuit 20 are in phase with the impulses in the circuit which includes the coil |30, the circuit is completed through grid |22 to coil |34 thereby causing rotation of the motor |40 in one direction. If the impulses in circuit i0 |20 are out of phase with the circuit which includes coil |30, the circuit is completed through grid |24 to coil |36, thereby causing motor |40 to rotate in the opposite direction. The phasing of the impulses in circuit |20 is dependent upon whether the stroke lengthens beyond its normal stroke or shortens to a stroke less than the normal length.

The rotation of the motor |40 is in one directionl if the stroke shortens and in the other direction if the stroke lengthens. The rotation of the motor may be used for adjusting the opening of the spill ports by which the eiective volume of the compressor may be adjusted, or for adjusting the quantity of fuel, or for adjusting the pressure in the air spring or for such other control as may be desired. To prevent over-control the motor |40 as it rotates also changes the seating of contact I|4 on resistance |02, thereby providing a resetting mechanism to stop the motor |40 after a predetermined amount of rotation in either direction.

In order that the control device may be responsive to altitude changes, the contact ||2 may be connected to an atmospheric bellows |48 so that the position of the contact ||2 is moved in response to changes in atmospheric pressure.

In order to have a direct indication of the position of the end of the piston stroke, an indicator |50 which may be in the form of an A. C. volt meter is connected across coil 82 and may be calibrated to indicate the change in the end position of the stroke, since the change in position will be a function of the change in electrical energy in coil 82.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as deilned g by the following claims.

I claim:

1. In a free-piston unit, a piston assembly, engine and compressor cylinders in'whlch said assembly reciprocates, and means responsive to l movement of the piston assembly for indicating electrically the position of the piston assembly in the cylinders, said means including a reversible motor adapted to actuate a control for the unit, an electrical circuit including said motor, a coil movable in response to the piston movement and adapted by its movement to procure changes in the circuit for procuring operation of said motor and means responsive to operation of said motor for procuring changes in the circuit to limit the zo operation of the motor proportional to the change in the position of the piston assembly.

2. In a free-piston unit, a piston assembly, engine and compressor cylinders in which said assembly reciprooates, and means responsive to movement of the piston assembly for indicating electrically the end position of the piston stroke of the piston assembly in the cylinders, said means including a reversible motor adapted to operate a control for the unit, an electrical circuit, a coil 80 movable in response to the piston movement and adapted by its movement to procure changes in the circuit, means controlled by said circuit for procuring operation of said motor and means responsive to operation of the motor for procuring other changes in the circuit to limit the operation of the motor proportionally to the change in the end position of the strokes of the piston assembly.

3. In a. free-piston unit, a piston assembly, engine and compressor cylinders in which said assembly reciprocates, said assembly having a variable stroke, and means operative during operation of the unit and responsive to movement of the piston assembly within the cylinders for indicating electrically the end position of the stroke of the piston assembly in the cylinder, said electrical means including a xed coil, a movable coil adjacent to the xed coil and movable with respect thereto in response to piston movement, said movable coil being connected to and actuated by the piston assembly adjacent to one end of the stroke of the piston assembly. an electrical circuit for supplying energy at a predetermined rate to one of said coils, and electrical indicating means for indicating the change in energy in the other in position of the coils when the position of the piston at the ends of successive strokes is changed.

4. In a free-piston unit, a piston assembly, enw gine and compressor cylinders in which said assembly rcciprocates, control means for the unit, and reversible actuating means for said control means, in combination with electrical means responsive to movement of the piston assembly for u controlling the direction of movement of said actuating means in response to changes in the end position of the stroke of the piston assembly, said electrical means including a movable coil actuated by and responsive to movement of the piston assembly at one end of the piston stroke, an electrical circuit including said coil and being normally in balance when the end of the piston stroke is at the normal position, and switch means responsive to an unbalance in said circuit for energizing the actuating means.

of said coils resulting from the relative change- 5. In a free-piston unit, a piston assembly, engine and compressor cylinders in which said assembly reciprocates, control means for the unit,

and an electrical motor adapted to actuate said control means for the unit, in combination with means responsive to changes in the end positions of the strokes of the piston assembly for controlling the motor, said means including -a movable coil actuated by and responsive to movement of the piston assembly at one end of the piston stroke, an electrical circuit including said coil and being normally in balance when the end of the piston stroke is at the normal position, and switch means responsive to an unbalance in said circuit for energizing the motor means.

6. In a free-piston unit, a piston assembly, en-

gine and compressor cylinders in which said asand being normally in balance when the end of the piston stroke is at the normal position, and switch means responsive to an unbalance in said circuit for energizing the motor means, and other means for separately affecting the operation of said motor by changing the normal balance of the circuit.

7. In a free-piston unit, a piston assembly having a variable length stroke, engine and compressor cylinders in which said assembly reciprocates, an air spring acting on said assembly, expanslon of gas in the engine cylinder moving the piston assembly in one direction and the air spring moving the assembly in the opposite direction, control means for the unit, and means responsive to movement o i' the piston assembly for indicating electrically the position of the piston assembly in the cylinder, said means including a reversible motor adapted to actuate the control means for the unit, an electrical circuit, a coil movable in response to the piston movement and adapted by its movement to procure changes in the circuit, and means controlled by the changes in said circuit for procuring operation oi' said motor. f

,8. In a free-piston unit, a piston assembly having a variable length stroke, engine and compressor cylinders in which said assembly reciprocates, an air spring acting on said assembly,

, expansion of gas in the engine cylinder moving the piston assembly in one direction and the air spring moving the assembly in the opposite direction, control means for the unit, and means responsive to movement of the piston assembly for indicating electrically the position of the piston assembly in the cylinders, said means including a reversible motor adapted to actuate the control means for the unit, an electrical circuit, a coil movable in. response to the piston movement and adapted by its movement to--pro cure changes in the circuit, a switch control-led by said circuit, and means responsive to changes in said circuit for moving the switch to control the direction of rotation of the motor.

9. In a free-*piston unit, a piston assembly having a variable length stroke, engine and compressor cylinders in which said assembly reciprocates, an air spring acting on said assembly, expansion of gas in .the engine cylinder moving the piston assembly in one direction and the air spring moving the assembly in the opposite direction, control means for the unit, and means responsive to movement of the piston assembly for indicating electrically the position of the piston assembly in the cylinders, said means including a reversible motor, adapted to actuate the control means for the unit, an electrical circuit, a coil movable in response to the piston movement at one end of the piston stroke and adapted by its movement to procure changes in the circuit, a switch controlled by said circuit, and means responsive to changes in said circuit for moving the switch to control the direction of rotation of the motor, and other means operating in conjunction with the coil for separately procuring changes in the circuit.

10. In a free-piston unit, a piston assembly having a variable length stroke, engine and compressor cylinders in which said assembly reciprocates, an air spring acting on said assembly, expansion of gas in the engine cylinder moving the piston assembly in one direction and the air 40 by its movement to procure changes in the cir- Number Name Date 2,064,976 Janicke Dec. 22, `1986 2,072,984 Haskins Mar. 9, 1937 2,090,709 Steiner Aug. 24, 1987 2,173,311 Pescara oct. 31, 1939 2,191,552 Zimmermann Feb. 27, 1940 2,200,892 Pescara May 14, 1940 2,259,587 Rush Oct. 21.1941 2,361,462 Dickinson Oct. 31. 1944 2,4o3,194 Roberts July 2, 194s 2,408,362 Beale Oct. 1, 1946 2,426,297 Cooper Aug. l26, 1947 FOREIGN PATENTS Number Country Dato 208,612 Switzerland 1940 370,956 Italy 1939 Great Britain 1987 cuit, and a switch movable in response to changes in the circuit, said switch controlling the direction of rotation of the motor.

ANDREW KAIJI'INSKY.

' REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS 

